单位名 金额
单位1 948.34
单位2 4324
单位5 324

final String wsFileDir = "H:/OtherWorkDocs/ws"; // 原始数据存放的目录
final String resFilePath = "H:/OtherWorkDocs/output/jan_feb_mar_sum.xls";
RWExcel rwExcel = new RWExcel(); // 操作xls的实例
// 获取所有的名称并排序
TreeSet nameSet = rwExcel.getNameSet(wsFileDir);
// 将名称与下标存入map中
HashMap nameRowHashMap = rwExcel.getNameRowHashMap(nameSet);
File wsDir = new File(wsFileDir); // 源文件目录
File[] sourceFiles = wsDir.listFiles();
// 存储单位名称与金额对应的数据
List> dataList = new ArrayList<>(10);
if (sourceFiles != null) {
 for (File sF : sourceFiles) {
  // 装载数据
  dataList.add(rwExcel.getSourceData(sF.getAbsolutePath()));
 }
}
// 原始数据已经全部读出来，和名称一次性全部写入
rwExcel.writeAllToResFile(resFilePath, nameRowHashMap, dataList);
// 补充标题栏的标题
if (null != sourceFiles) {
 int col = 1; // 起始列的序号
 for (File f : sourceFiles) {
  String fileName = f.getName();
  String name = fileName.substring(0, fileName.length() - 4);
  rwExcel.updateContent(resFilePath, name, 0, col);
  col++;
 }
}

public class RWExcel {
 /**
  * 存储名称
  */
 private TreeSet nameTreeSet = new TreeSet<>();
 /**
  * 名称以及排列的下标号
  */
 private HashMap nameRowMap = new HashMap<>();
 public TreeSet getNameSet(String wsPath) {
  try {
   File wsDir = new File(wsPath);
   if (wsDir.exists() && wsDir.isDirectory()) {
    println("工作目录存在");
    File[] files = wsDir.listFiles();
    if (files != null && files.length > 0) {
     for (File cFile : files) {
      getNamesFromFile(cFile, this.nameTreeSet);
     }
    }
   }
  } catch (Exception e) {
   e.printStackTrace();
  }
  this.nameTreeSet.comparator();
  return this.nameTreeSet;
 }
 /**
  * 将名称Set排序后存入HashMap
  * 下标从1开始
  */
 public HashMap getNameRowHashMap(TreeSet nameSet) {
  nameSet.comparator();
  int index = 1;
  for (String name : nameSet) {
   this.nameRowMap.put(name, index);
   index++;
  }
  return this.nameRowMap;
 }
 /**
  * 所有数据存入表格
  */
 public void writeAllToResFile(String resFilePath, Map nameMap, List> dataList) {
  File resFile = new File(resFilePath);
  if (!resFile.exists()) {
   try {
    resFile.createNewFile();
   } catch (IOException e) {
    e.printStackTrace();
   }
  }
  if (resFile.exists()) {
   try {
    // 先写名称
    WritableWorkbook wwb = Workbook.createWorkbook(resFile);
    WritableSheet ws = wwb.createSheet("sum", 0);
    Label label = new Label(0, 0, "单位名称");
    ws.addCell(label);
    for (Map.Entry entry : nameMap.entrySet()) {
     Label nameLabel = new Label(0, entry.getValue(), entry.getKey());
     ws.addCell(nameLabel);
     for (int j = 0; j < dataList.size(); j++) {
      Number zeroCell = new Number(j + 1, entry.getValue(), 0);
      ws.addCell(zeroCell);
     }
    }
    for (int dataColumn = 0; dataColumn < dataList.size(); dataColumn++) {
     HashMap dataMap = dataList.get(dataColumn);
     // 遍历这个map 将所有的数据对应填入
     for (Map.Entry dataEntry : dataMap.entrySet()) {
      int row = nameRowMap.get(dataEntry.getKey());
      Number numberCell = new Number(dataColumn + 1, row, dataEntry.getValue());
      ws.addCell(numberCell);
     }
    }
    wwb.write();
    wwb.close();
   } catch (Exception e) {
    e.printStackTrace();
   }
  }
 }
 private void getNamesFromFile(File inputFile, TreeSet hashSet) throws IOException, BiffException {
  Workbook workbook;
  InputStream is = new FileInputStream(inputFile);
  workbook = Workbook.getWorkbook(is);
  Sheet sheet0 = workbook.getSheet(0);
  int columnSum = sheet0.getColumns(); // 总列数
  int rsRows = sheet0.getRows();  // 总行数
  // 从1下标开始
  for (int i = 1; i < rsRows; i++) {
   Cell cell = sheet0.getCell(0, i);
   if (!isEmpty(cell.getContents())) {
    hashSet.add(cell.getContents());
   }
  }
  println("此文件行数减一 = " + (rsRows - 1) + " , 当前获取到的所有单位数 " + hashSet.size());
 }
 /**
  * 从原始数据中读取并匹配的存入结果文件中
  */
 private HashMap getSourceData(String source) {
  File sFile = new File(source);
  if (!sFile.exists()) {
   System.out.println("原始文件不存在 复制失败!");
   return null;
  }
  // 读取源文件中的所有数据 <单位名称, 数值>
  HashMap sourceHashMap = new HashMap<>();
  try {
   Workbook sourceWs = Workbook.getWorkbook(sFile);
   Sheet sSheet0 = sourceWs.getSheet(0);
   int sTotalRows = sSheet0.getRows();  // 总行数
   for (int i = 1; i < sTotalRows; i++) {
    Cell cellKey = sSheet0.getCell(0, i);
    Cell cellValue = sSheet0.getCell(1, i);
    if (!isEmpty(cellKey.getContents()) && !isEmpty(cellValue.getContents())) {
     sourceHashMap.put(cellKey.getContents(), Float.valueOf(cellValue.getContents()));
    }
   }
   println(source + " 读取到的数据数量 = " + sourceHashMap.size());
  } catch (Exception e) {
   e.printStackTrace();
  }
  return sourceHashMap;
 }
 public void updateContent(String filePath, String input, int row, int column) {
  File file = new File(filePath);
  if (!file.exists()) {
   System.out.println(filePath + " does not exist!");
   return;
  }
  try {
   Workbook sourceWb = Workbook.getWorkbook(file);
   WritableWorkbook wwb = Workbook.createWorkbook(file, sourceWb);
   WritableSheet wSheet0 = wwb.getSheet(0);
   Label label = new Label(column, row, input);
   wSheet0.addCell(label);
   wwb.write();
   wwb.close();
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
 public RWExcel() {
 }
 private static boolean isEmpty(String str) {
  if (null == str) {
   return true;
  }
  return str.isEmpty();
 }
 private static void println(String in) {
  System.out.println(in);
 }
}

单位名称 1月总金额 2月总金额 3月总金额
单位1 0 59.29999924 948.3400269
单位10 0 0 494.2000122
单位11 0 0 11.19999981
单位12 0 0 1.25
单位15 49.36000061 0 0
单位2 0 0 4324
单位24 0 34 0
单位5 0 23123 324
单位6 0 161.2599945 0